Henrik Vedel - Academia.edu (original) (raw)

Papers by Henrik Vedel

EGUGA, Apr 1, 2016

&... more <p>E-GVAP (the EIG EUMETNET GNSS Water Vapour Programme) is an operational service providing atmospheric delay estimates for use in operational meteorology in near real-time. This is done in a close collaboration between geodetic and meteorological institutions. The use of the GNSS delay estimates is found to increase the skill of weather forecasts. By the start of 2019 E-GVAP did, along with EUMETNET itself, entered a new phase. In E-GVAP 4 the main product will still be zenith total delays (ZTD), with a focus on improving timeliness, in support of the high resolution, local weather models with frequent updates being set up these years. But in addition there will be focus on GNSS derived slant total delay (STD) estimates. Several of the weather models used in Europe are being prepared for STD assimilation. The STDs provide additional information, on atmospheric asymmetries, on top of the information contained in a single ZTD estimate</p>

The Astrophysical Journal, Jul 10, 1998

Undisrupted wind observations at 10m level (u10, v10) have been analyzed for recent decadal chang... more Undisrupted wind observations at 10m level (u10, v10) have been analyzed for recent decadal changes with respect to surface geostrophic winds (ug, vg) and 10m winds from ERA5 (u10E, v10E).Thus, we analyze the difference between (u10, v10) and (ug, vg), and between (u10, v10) and (u10E, v10E). The underlying hypothesis is that the effective roughness length has increased during the last 30 years in the Danish area, including surrounding seas, due to the extensive expansion of both on- and off-shore wind turbine installations in Denmark and neighboring countries.Theoretically a gradual increase in roughness length will lead to a reduction in near-surface winds with respect to undisturbed conditions, i.e., the recent "climatic roughness length" before the present analysis. We already know from extensive measurement campaigns - mostly offshore - that direct wake effects from large wind farms can be quite substantial - with reduced near surface wind - in the wake, sometimes up to almost 100 km downstream of the wind farm.Furthermore, the cross-isobaric flow will change, resulting in a potential enhanced Ekman pumping in the planetary boundary layer, and thereby an accelerated spin down process of atmospheric synoptic scale weather systems, including induced precipitation in decaying low-pressure systems. Therefore, this is also analyzed.It is well known that we have natural decadal and interdecadal fluctuations in the near surface wind, which are not related to changing regional surface characteristics. This is the reason that we do not consider the direct wind-observations but rather the anomalies with respect to ERA5 surface geostrophic winds and near surface winds, which are only marginally "polluted" by the existence of wind farms, since these are not build into the re-analysis system (model)We have obtained results showing a change in the wind characteristics analyzed, which is in line with the original hypothesis.

AGU Fall Meeting Abstracts, Dec 1, 2019

EGU General Assembly Conference Abstracts, May 1, 2014

Journal of Atmospheric and Oceanic Technology, Aug 1, 2020

Meteorology and Atmospheric Physics, Jul 11, 2015

At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include as... more At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include assimilation of 2D precipitation rates derived from weather radar observations. The assimilation is performed using a nudging-based technique. Here the rain rates are used to estimate the changes in the vertical profile of horizontal divergence needed to induce the observed rain rate. Verification of precipitation forecasts for a 17-day period in August 2010 based on the NWP nowcasting system is presented and compared to a reference without assimilation of precipitation data. In Denmark, this period was particularly rainy, with several heavy precipitation events. Three of these events are studied in detail. The verification is mainly based on scatter plots and fractions skill scores, which give scale-dependant indicators of the spatial skill of the forecasts. The study shows that the inclusion of precipitation observations has a positive impact on the spatial skill of the forecasts. This positive impact is the largest in the first hour, and then gradually decreases. On the average, the forecasts with assimilation of precipitation are skilful after 4 h on scales down to a few tens of kilometers. For the events studied, the assimilation improves the forecasted frequencies of heavy and light precipitation relative to the control, while there is some tendency to overpredict intermediate precipitation levels.

The Astrophysical Journal, Jun 20, 1998

. With increasing number and proximity of wind farms it becomes crucial to consider wind farm eff... more . With increasing number and proximity of wind farms it becomes crucial to consider wind farm effects (WFE) in the numerical weather prediction (NWP) models used to forecast power production. Furthermore, these WFE are also expected to affect other weather-related parameters at least locally. Thus, we implement the explicit wake parameterization (EWP) in the NWP model HARMONIE-AROME (hereafter HARMONIE) along-side the existing wind farm parameterization (WFP) by Fitch et al. (2012) (FITCH). We evaluate and compare the two WFPs against research flight measurements as well as against similar simulations performed with the Weather Research and Forecasting model (WRF) using case studies. The case studies include a case for WFE above a wind farm as well as two cases for WFE at hub height in the wake of farms. The results show that EWP and FITCH have been correctly implemented in HARMONIE. For the simulated cases, EWP underestimates the WFE on wind speed and strongly underestimates the effect on turbulent kinetic energy (TKE). FITCH agrees better with the observations and WFE on TKE are particularly well captured by HARMONIE-FITCH. After this successful evaluation, simulations with all wind turbines in Europe will be performed with HARMONIE and presented in the second part of this paper series.

AGU Fall Meeting Abstracts, Dec 1, 2012

EGU General Assembly Conference Abstracts, Apr 1, 2012

ABSTRACT

Geophysical Research Letters, Aug 20, 2022

Intense convective storms can be hazardous when occurring over large populated cities. In a chang... more Intense convective storms can be hazardous when occurring over large populated cities. In a changing climate, decision makers and the general public increasingly need to be able to better understand if and to what extent these storms are influenced by anthropological climate change and what to expect as climate continues to warm. Unfortunately due to their limited ability to resolve small‐scale features in models, convective storms remain a challenge to the modeling community. Here, we use a forecast‐ensemble based method using a convection permitting model with full data‐assimilation, to assess the risk of exceeding certain precipitation thresholds related to a critical cloudburst event that occurred over Copenhagen, Denmark. Our results show that this set‐up is representing well the overall observed intensities. By adapting a pseudo‐global warming approach, we show that both the risk for flooding and the risk for reaching unprecedented precipitation intensity increases resulting from further warming.

Quarterly Journal of the Royal Meteorological Society, 2007

Monthly Notices of the Royal Astronomical Society, Dec 1, 1994

The Astrophysical Journal, Jul 10, 1999

&... more <p>E-GVAP (the EIG EUMETNET GNSS Water Vapour Programme) is an operational service providing atmospheric delay estimates for use in operational meteorology in near real-time. This is done in a close collaboration between geodetic and meteorological institutions. The use of the GNSS delay estimates is found to increase the skill of weather forecasts. By the start of 2019 E-GVAP did, along with EUMETNET itself, entered a new phase. In E-GVAP 4 the main product will still be zenith total delays (ZTD), with a focus on improving timeliness, in support of the high resolution, local weather models with frequent updates being set up these years. But in addition there will be focus on GNSS derived slant total delay (STD) estimates. Several of the weather models used in Europe are being prepared for STD assimilation. The STDs provide additional information, on atmospheric asymmetries, on top of the information contained in a single ZTD estimate</p>

<p><span>On the evening on July 2, 2011 a severe clou... more <p><span>On the evening on July 2, 2011 a severe cloud burst occurred in the Copenhagen area. During the late afternoon deep moist convection developed over nearby Skåne (the southernmost part of Sweden) in an airstream from east-northeast. In the early evening the DMC passed over Øresund to Copenhagen, where it created a severe flash flood. Between 90 and 135 mm of precipitation in less than 2 hours was recorded ooding cellars, streets, and key roads. The deluge caused 6 billion Danish kroner in damage. Although that such extreme events are rare, the impacts on society is important and should be understood under a warmer climate. Although regional climate models have recently reached the convection permitting resolution, reproducing such events is still challenging.</span></p><p><span>Several studies suggest that extreme precipitations should increase under a future warmer climate using transient simulation or a pseudo-warming approach. It is still unclear how such event would behave under warmer or colder synoptic conditions. Using a forecast-ensemble method, but keeping a climate perspective, this study assesses the risk rising from such an event under otherwise almost identical, but warmer or colder conditions. With this set-up, we find that the development of the system that resulted in observed downpour exhibit quite a sensitivity to the initial conditions and contrary to a linear thinking, the risk of flooding is decreasing as the climate warms due to the inhibition of the CAPE by the additional lapse-rate anomalies used in this study. We therefore propose that the PGW method should be used with caution and that extreme precipitation events also in transient simulations of future climates need to be studied in detailed to address the limitations to models ability to produce those most extreme and by nature inherently rare events.</span></p>

Monthly Notices of the Royal Astronomical Society, Mar 1, 1998

The Astrophysical Journal, Aug 1, 1990

EGU General Assembly Conference Abstracts, Apr 1, 2018

EGUGA, Apr 1, 2016

&... more <p>E-GVAP (the EIG EUMETNET GNSS Water Vapour Programme) is an operational service providing atmospheric delay estimates for use in operational meteorology in near real-time. This is done in a close collaboration between geodetic and meteorological institutions. The use of the GNSS delay estimates is found to increase the skill of weather forecasts. By the start of 2019 E-GVAP did, along with EUMETNET itself, entered a new phase. In E-GVAP 4 the main product will still be zenith total delays (ZTD), with a focus on improving timeliness, in support of the high resolution, local weather models with frequent updates being set up these years. But in addition there will be focus on GNSS derived slant total delay (STD) estimates. Several of the weather models used in Europe are being prepared for STD assimilation. The STDs provide additional information, on atmospheric asymmetries, on top of the information contained in a single ZTD estimate</p>

The Astrophysical Journal, Jul 10, 1998

Undisrupted wind observations at 10m level (u10, v10) have been analyzed for recent decadal chang... more Undisrupted wind observations at 10m level (u10, v10) have been analyzed for recent decadal changes with respect to surface geostrophic winds (ug, vg) and 10m winds from ERA5 (u10E, v10E).Thus, we analyze the difference between (u10, v10) and (ug, vg), and between (u10, v10) and (u10E, v10E). The underlying hypothesis is that the effective roughness length has increased during the last 30 years in the Danish area, including surrounding seas, due to the extensive expansion of both on- and off-shore wind turbine installations in Denmark and neighboring countries.Theoretically a gradual increase in roughness length will lead to a reduction in near-surface winds with respect to undisturbed conditions, i.e., the recent "climatic roughness length" before the present analysis. We already know from extensive measurement campaigns - mostly offshore - that direct wake effects from large wind farms can be quite substantial - with reduced near surface wind - in the wake, sometimes up to almost 100 km downstream of the wind farm.Furthermore, the cross-isobaric flow will change, resulting in a potential enhanced Ekman pumping in the planetary boundary layer, and thereby an accelerated spin down process of atmospheric synoptic scale weather systems, including induced precipitation in decaying low-pressure systems. Therefore, this is also analyzed.It is well known that we have natural decadal and interdecadal fluctuations in the near surface wind, which are not related to changing regional surface characteristics. This is the reason that we do not consider the direct wind-observations but rather the anomalies with respect to ERA5 surface geostrophic winds and near surface winds, which are only marginally "polluted" by the existence of wind farms, since these are not build into the re-analysis system (model)We have obtained results showing a change in the wind characteristics analyzed, which is in line with the original hypothesis.

AGU Fall Meeting Abstracts, Dec 1, 2019

EGU General Assembly Conference Abstracts, May 1, 2014

Journal of Atmospheric and Oceanic Technology, Aug 1, 2020

Meteorology and Atmospheric Physics, Jul 11, 2015

At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include as... more At the Danish Meteorological Institute, the NWP nowcasting system has been enhanced to include assimilation of 2D precipitation rates derived from weather radar observations. The assimilation is performed using a nudging-based technique. Here the rain rates are used to estimate the changes in the vertical profile of horizontal divergence needed to induce the observed rain rate. Verification of precipitation forecasts for a 17-day period in August 2010 based on the NWP nowcasting system is presented and compared to a reference without assimilation of precipitation data. In Denmark, this period was particularly rainy, with several heavy precipitation events. Three of these events are studied in detail. The verification is mainly based on scatter plots and fractions skill scores, which give scale-dependant indicators of the spatial skill of the forecasts. The study shows that the inclusion of precipitation observations has a positive impact on the spatial skill of the forecasts. This positive impact is the largest in the first hour, and then gradually decreases. On the average, the forecasts with assimilation of precipitation are skilful after 4 h on scales down to a few tens of kilometers. For the events studied, the assimilation improves the forecasted frequencies of heavy and light precipitation relative to the control, while there is some tendency to overpredict intermediate precipitation levels.

The Astrophysical Journal, Jun 20, 1998

. With increasing number and proximity of wind farms it becomes crucial to consider wind farm eff... more . With increasing number and proximity of wind farms it becomes crucial to consider wind farm effects (WFE) in the numerical weather prediction (NWP) models used to forecast power production. Furthermore, these WFE are also expected to affect other weather-related parameters at least locally. Thus, we implement the explicit wake parameterization (EWP) in the NWP model HARMONIE-AROME (hereafter HARMONIE) along-side the existing wind farm parameterization (WFP) by Fitch et al. (2012) (FITCH). We evaluate and compare the two WFPs against research flight measurements as well as against similar simulations performed with the Weather Research and Forecasting model (WRF) using case studies. The case studies include a case for WFE above a wind farm as well as two cases for WFE at hub height in the wake of farms. The results show that EWP and FITCH have been correctly implemented in HARMONIE. For the simulated cases, EWP underestimates the WFE on wind speed and strongly underestimates the effect on turbulent kinetic energy (TKE). FITCH agrees better with the observations and WFE on TKE are particularly well captured by HARMONIE-FITCH. After this successful evaluation, simulations with all wind turbines in Europe will be performed with HARMONIE and presented in the second part of this paper series.

AGU Fall Meeting Abstracts, Dec 1, 2012

EGU General Assembly Conference Abstracts, Apr 1, 2012

ABSTRACT

Geophysical Research Letters, Aug 20, 2022

Intense convective storms can be hazardous when occurring over large populated cities. In a chang... more Intense convective storms can be hazardous when occurring over large populated cities. In a changing climate, decision makers and the general public increasingly need to be able to better understand if and to what extent these storms are influenced by anthropological climate change and what to expect as climate continues to warm. Unfortunately due to their limited ability to resolve small‐scale features in models, convective storms remain a challenge to the modeling community. Here, we use a forecast‐ensemble based method using a convection permitting model with full data‐assimilation, to assess the risk of exceeding certain precipitation thresholds related to a critical cloudburst event that occurred over Copenhagen, Denmark. Our results show that this set‐up is representing well the overall observed intensities. By adapting a pseudo‐global warming approach, we show that both the risk for flooding and the risk for reaching unprecedented precipitation intensity increases resulting from further warming.

Quarterly Journal of the Royal Meteorological Society, 2007

Monthly Notices of the Royal Astronomical Society, Dec 1, 1994

The Astrophysical Journal, Jul 10, 1999

&... more <p>E-GVAP (the EIG EUMETNET GNSS Water Vapour Programme) is an operational service providing atmospheric delay estimates for use in operational meteorology in near real-time. This is done in a close collaboration between geodetic and meteorological institutions. The use of the GNSS delay estimates is found to increase the skill of weather forecasts. By the start of 2019 E-GVAP did, along with EUMETNET itself, entered a new phase. In E-GVAP 4 the main product will still be zenith total delays (ZTD), with a focus on improving timeliness, in support of the high resolution, local weather models with frequent updates being set up these years. But in addition there will be focus on GNSS derived slant total delay (STD) estimates. Several of the weather models used in Europe are being prepared for STD assimilation. The STDs provide additional information, on atmospheric asymmetries, on top of the information contained in a single ZTD estimate</p>

<p><span>On the evening on July 2, 2011 a severe clou... more <p><span>On the evening on July 2, 2011 a severe cloud burst occurred in the Copenhagen area. During the late afternoon deep moist convection developed over nearby Skåne (the southernmost part of Sweden) in an airstream from east-northeast. In the early evening the DMC passed over Øresund to Copenhagen, where it created a severe flash flood. Between 90 and 135 mm of precipitation in less than 2 hours was recorded ooding cellars, streets, and key roads. The deluge caused 6 billion Danish kroner in damage. Although that such extreme events are rare, the impacts on society is important and should be understood under a warmer climate. Although regional climate models have recently reached the convection permitting resolution, reproducing such events is still challenging.</span></p><p><span>Several studies suggest that extreme precipitations should increase under a future warmer climate using transient simulation or a pseudo-warming approach. It is still unclear how such event would behave under warmer or colder synoptic conditions. Using a forecast-ensemble method, but keeping a climate perspective, this study assesses the risk rising from such an event under otherwise almost identical, but warmer or colder conditions. With this set-up, we find that the development of the system that resulted in observed downpour exhibit quite a sensitivity to the initial conditions and contrary to a linear thinking, the risk of flooding is decreasing as the climate warms due to the inhibition of the CAPE by the additional lapse-rate anomalies used in this study. We therefore propose that the PGW method should be used with caution and that extreme precipitation events also in transient simulations of future climates need to be studied in detailed to address the limitations to models ability to produce those most extreme and by nature inherently rare events.</span></p>

Monthly Notices of the Royal Astronomical Society, Mar 1, 1998

The Astrophysical Journal, Aug 1, 1990

EGU General Assembly Conference Abstracts, Apr 1, 2018